docs: def _make_association(self, subject_id, object_id, rel_id, pubmed_ids):
          """
          Make a reified association given an array of pubmed identifiers.
  
          Args:
              :param subject_id  id of the subject of the association (gene/chem)
              :param object_id  id of the object of the association (disease)
              :param rel_id  relationship id
              :param pubmed_ids an array of pubmed identifiers
          Returns:
              :return None
  
          """
  
          # TODO pass in the relevant Assoc class rather than relying on G2P
          assoc = G2PAssoc(self.graph, self.name, subject_id, object_id, rel_id)
          if pubmed_ids is not None and len(pubmed_ids) > 0:
              for pmid in pubmed_ids:
                  ref = Reference(
                      self.graph, pmid, self.globaltt['journal article'])
                  ref.addRefToGraph()
                  assoc.add_source(pmid)
                  assoc.add_evidence(self.globaltt['traceable author statement'])
  
          assoc.add_association_to_graph()
          return